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1.
RNA was degraded at 60 degrees C for 24 h by halophilic nuclease H in supernatants from broth cultures of Micrococcus varians subsp. halophilus containing 12% NaCl. Since contaminating 5'-nucleotidase exhibited almost no activity under these conditions, the 5'-GMP formed could be recovered from the reaction mixture, and the yield was 805 mg from 5 g of RNA. 相似文献
2.
We investigated the effects of near-infrared irradiation on the photoconversion of Chenopodium album water-soluble chlorophyll-binding protein (CaWSCP) in the presence of sodium hydrosulfite and found a further photoconversion from CP742 to CP763, a novel form of CaWSCP. Interestingly, one-third of the absorption peak at 668 nm was recovered in CP763, but re-irradiation under oxidative conditions eliminated the photo convertibility of CaWSCP. 相似文献
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Effects of nitrates and calcium channel blockers on Ca2+-ATPase in the microsomal fraction of porcine coronary artery smooth muscle cells 总被引:1,自引:0,他引:1
The effects of the antianginal drugs nitroglycerin, nicorandil, diltiazem, verapamil and nicardipine on the activity of calcium-stimulated magnesium-dependent ATPase (Ca2+-ATPase) were investigated in the microsomal fraction from porcine coronary artery smooth muscle cells. Two discrete Ca2+-dependent ATPase components were observed: [1] a high affinity component, which was a specific Ca2+-ATPase, [with a half saturation constant for Ca2+ (Km) of 0.44 microM, and maximum velocity (Vmax) of 124.3 pmol of phosphate (Pi) released/micrograms of protein/30 min]: [2] a low affinity component in which Ca2+ could be replaced by Mg2+ without loss of its activity. Nitroglycerin and nicorandil (1 microM and 10 microM) both stimulated the activity of the Ca2+-ATPase significantly [142 +/- 12 (mean +/- standard error), and 137 +/- 10% of the control with nitroglycerin, and 152 +/- 17 and 135 +/- 20% with nicorandil] at a Ca2+ concentration of 0.3 microM. Diltiazem, verapamil and nicardipine did not cause significant stimulation. Nitroglycerin and nicorandil (1 microM), significantly decreased the Km for Ca2+ from the control value of 0.44 +/- 0.06 microM to 0.26 +/- 0.03 and 0.22 +/- 0.03 microM, respectively. Nitroglycerin and nicorandil may dilate coronary arteries by stimulating this Ca2+ extrusion pump enzyme through reduction of intracellular Ca2+ in smooth muscle cells. 相似文献
7.
Characterization and physiological function of glutathione reductase in Euglena gracilis z. 总被引:2,自引:0,他引:2 下载免费PDF全文
The purified glutathione reductase was homogeneous on polyacrylamide-gel electrophoresis. It had an Mr of 79,000 and consisted of two subunits with a Mr of 40,000. The activity was maximum at pH 8.2 and 52 degrees C. It was specific for NADPH but not for NADH as the electron donor; the reverse reaction was not observed. The Km values for NADPH and GSSG were 14 and 55 microM respectively. The enzyme activity was markedly inhibited by thiol inhibitors and metal ions such as Hg2+, Cu2+ and Zn2+. Euglena cells contained total glutathione at millimolar concentration. GSH constituted more than 80% of total glutathione in Euglena under various growth conditions. Glutathione reductase was located solely in cytosol, as were L-ascorbate peroxidase and dehydroascorbate reductase, which constitute the oxidation-reduction cycle of L-ascorbate [Shigeoka et al. (1980) Biochem. J. 186, 377-380]. These results indicate that glutathione reductase functions to maintain glutathione in the reduced form and to accelerate the oxidation-reduction of L-ascorbate, which scavenges peroxides generated in Euglena cells. 相似文献
8.
Yasushi Harada 《Journal of Ethology》1989,7(1):17-25
A theory on the evolution of human primary sex ratio is proposed. Effects of parental preference for sons, reflected in birth
control based on offspring sex ratio and female biased infanticide, on the evolution of primary sex ratio are analyzed. Both
are shown to select for female bias in primary sex ratio. The gene-culture coevolution of female infanticide and primary sex
ratio is also studied and it is shown that female infanticide develops more in societies in which the father plays a more
important role in the transmission of culture than the mother does. 相似文献
9.
R Morita S Morimoto E Koh K Fukuo S Kim K Itoh K Taniguchi T Onishi T Ogihara 《Biochemistry international》1989,18(3):647-653
Low density lipoprotein (LDL), a major cholesterol-carrying lipoprotein in the plasma, binds to its receptor through apoprotein B (Apo-B). The addition of LDL and Apo-B induced rapid (5 s), but transient increase in the inositol 1,4,5-trisphosphate (Ins-1,4,5-P3) level with K0.5 values of 1.1 and 0.07 microgram/ml, accompanied by increases of cytosolic free Ca2+ concentration [( Ca2+]i), in vascular smooth muscle cells (VSMC). The increases by LDL and Apo-B were both reduced by pretreatment of the VSMC with pertussis toxin. The early change in Ins-1,4,5-P3 involving a GTP-binding protein may function as an initial signal for the action of LDL in VSMC. 相似文献
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